410 THE QUESTION OF IMMUNITY AND ANTITOXINS 



changes, the body metabolism is affected owing to the distribution 

 of toxins, and it is to this cause that the chief symptoms of disease 

 are due. 



The Question of Immunity 



However the details of the modus operandi of the formation of 

 toxins are finally settled, we know that there comes a time when 

 the disease symptoms vanish, the disease declines, and the patient 

 recovers. In past times this was explained by saying that the 

 disease had exhausted itself, having gone "through" the body. In 

 a sense that idea is probably true ; but recently a number of 

 investigators have applied themselves to this problem, and with 

 some promising results. And it is now known that, as a result 

 of the action of the toxins in the body tissues, powers of 

 resistance are stimulated or conferred in or upon the body cells 

 affected. What has been found to be true of lower animals by 

 experimentation is now known to be true of the human body. It 

 has, therefore, become possible to inoculate resistant blood serum 

 into toxic blood with the result of opposing the toxins, and bringing 

 about a condition of resistance, and ultimately, recovery. Or, in 

 other words, one of the means of defence against the invasion of 

 such organisms which is possessed by the animal body is the 

 capacity to manufacture, and set free in the blood stream, sub- 

 stances which combine with the toxins and so render them inert. 

 By habituating a large animal, such as the horse, to the action of 

 toxin in increasing quantities, cells or fluids of its body can be 

 thereby so stimulated to produce and throw into the blood stream 

 antitoxins in excessive quantity, that the serum of the animals may 

 contain sufficient excess for its useful employment as a remedy for 

 the disease in man or animals. From such results it is but a step 

 to protective inoculation. 



Various protective inoculations against anthrax, for instance, 

 were practised as early as 1881, and the protected animals remained 

 healthy. In 1887 Wooldridge succeeded in protecting rabbits from 

 anthrax by a new method, by which he showed that the growth of 

 the anthrax bacillus in special culture fluids gave rise to a substance 

 which, when inoculated, conferred immunity. In 1889 and 1890 

 Hankin and Ogata worked at the subject, and announced the 

 discovery in the blood of animals which had died of anthrax of 

 substances which appeared to have an antagonistic and neutralising 

 effect upon the toxins of anthrax and upon the anthrax bacilli 

 themselves. These substances, they afterwards found, were products 

 of the anthrax bacillus. Behring and Kitasato arrived at much the 

 same results in tetanus and diphtheria. In 1890 they showed that 

 the blood serum of an animal which had been immunised against 



